Recently, in manufacture of electronic components and thin film devices, sputter films and evaporation films of Ag, Au, Cu, Al, and others are generally used as conductor films such as electrode films and wiring films. In the case of the substrate being made of ceramics or glass, a desired bonding strength is not obtained by a single material, and a layer of Cr, NiCr, having a strong adhesion strength with ceramics and glass is formed as an adhesive layer, and a multi-layer structure is composed.
For example, in a method of forming a conductor film by sputtering, a cathode having a material target of conductor film and a cathode having a material target of adhesive layer are disposed inside a vacuum container, confronting a substrate, and the inside of the vacuum container is evacuated to a degree of vacuum of about 10.sup.-6 Torr level, and then argon gas is introduced into the vacuum container to set the degree of vacuum at about 5.times.10.sup.-3 Torr.
Afterwards, by applying a direct-current voltage or high-frequency voltage to the cathode having material target of adhesive layer, plasma is generated inside the vacuum container, and an adhesive layer is formed on the substrate. Then, after stopping the application of voltage to the cathode having material target of adhesive layer, a direct-current voltage or high-frequency voltage is applied to the cathode having material target of conductor film, and plasma is generated inside the vacuum container, thereby forming a conductor film such as electrode film and wiring film on the adhesive layer formed beforehand.
When forming the adhesive layer in this manner, usually, by forming a film by heating the substrate over 100.degree. C. or annealing after forming a film, diffusion is induced in the interface of the conductor film and adhesive layer, and the bonding strength is improved on the interface of the conductor film and adhesive layer, so that peeling is prevented.
Some of ceramic substrates used in electronic components, cannot be heated over 100.degree. C. because, polarization occurs and piezo electric cannot be heated over 100.degree. C. because when the substrate temperature becomes high. Or, if the substrate is formed into a film or if the substrate is fixed on a film, it is not allowed to heat over the thermal deformation temperature of the film. In such cases, the bonding strength of the conductor film and adhesive layer cannot be improved by the above method, and peeling may occurs in the interface of the conductor film and adhesive layer in a later machining process, and the product life may be shortened or defects may occur.